Apple16X50UARTTypes.cpp   [plain text]


/*
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*/

/*
 * Apple16X50UARTTypes.cpp
 * Determine what type of UART is present, determine it's capabilities such as FIFO depth
 * and Master Clock frequency, and verify that it is working as expected.  These routines
 * are expected to be called prior to Apple16X50UARTSync::start(), and so
 *
 * 2002-04-10	dreece	created.
 */

#include "Apple16X50UARTTypes.h"
#include "Apple16X50BusInterface.h"

extern const IONamedValue gUARTnames[] = {
    { kUART_Unknown,	"Unknown" },	// Unknown UART
    { kUART_8250, 	"i8250" },	// Original ACE UART
    { kUART_16450,	"16450" },	// Improved UART, No FIFO
    { kUART_16550,	"16550" },	// Broken FIFO (unusable)
    { kUART_16550C,	"16550AF/C/CF"},// Working 16 byte FIFO
    { kUART_16C1550,	"16C1550" },	// Powerdown Mode & FIFO
    { kUART_16C650,	"16C650" },	// 32 byte FIFO
    { kUART_16C750,	"16C750" },	// 128 byte FIFO
    { kUART_16C950,	"16C950" },	// 128 byte FIFO
};

#define INB(reg)	( provider->getReg((reg), refCon) )
#define OUTB(reg,val)	( provider->setReg((reg), val, refCon) )

/* identifyUART() - This function attempts to identify the type of UART
 * present.  This routine is only intended to be run from the init method, before the chip is
 * active.
 */
tUART_Type //Apple16X50UARTSync::
identifyUART(Apple16X50BusInterface *provider, void *refCon)
{
    register UInt32 tmp;
 
    DEBUG_IOLog("Apple16X50UARTSync::identifyUART()\n");
    
    /* Verify that the BRG Divisor Register is accessable */
    OUTB(kREG_LineControl, kLCR_DivisorAccess);	/* Set DLAB=1 */
    OUTB(kREG_DivisorLSB, 0x5a);
    if (INB(kREG_DivisorLSB)!=0x5a) return kUART_Unknown;
    OUTB(kREG_DivisorLSB, 0xa5);
    if (INB(kREG_DivisorLSB)!=0xa5) return kUART_Unknown;
    OUTB(kREG_LineControl, 0x00);	/* Set DLAB=0 */
    DEBUG_IOLog("Apple16X50UARTSync::identifyUART() BRG Divisor is accessable\n");
    
    /* Verify that the Scratch Pad Register is accessable */
    OUTB(kREG_Scratch, 0x5a);
    if (INB(kREG_Scratch)!=0x5a) return kUART_8250;
    OUTB(kREG_Scratch, 0xa5);
    if (INB(kREG_Scratch)!=0xa5) return kUART_8250;
    DEBUG_IOLog("Apple16X50UARTSync::identifyUART() Scratchpad is accessable\n");
    
    /* Look for FIFO Bits in FIFO Control Register */
    OUTB(kREG_FIFOControl, kFIFO_Enable);
    tmp = INB(kREG_IRQ_Ident) & kIRQID_FIFOEnabled;
    OUTB(kREG_FIFOControl, 0x00);
    switch (tmp) {
        case 0x00 : return kUART_16450;
        case 0x40 : return kUART_16C650;
        case 0x80 : return kUART_16550;
        case 0xC0 : break;
    }
    DEBUG_IOLog("Apple16X50UARTSync::identifyUART() FIFO Enable status returned 0xC0\n");

    // Check for an alternate version of the Scratchpad...
    OUTB(kREG_LineControl, 0x00);
    OUTB(kREG_Scratch, 0xde);
    OUTB(kREG_LineControl, kLCR_DivisorAccess);
    OUTB(kREG_Scratch, 0xa9);
    tmp = INB(kREG_Scratch);
    OUTB(kREG_Scratch, 0x00);
    OUTB(kREG_LineControl, 0x00);
    if ((INB(kREG_Scratch) == 0xde) && (tmp == 0xa9)) {
        DEBUG_IOLog("Apple16X50UARTSync::identifyUART() Alternate Scratchpad is accessable\n");
        return kUART_16C650;
    }

    // Check for power-down bit in the 16X1550
    tmp = INB(kREG_ModemControl) & 0x80;
    OUTB(kREG_ModemControl, 0x00);
    if (tmp == 0x80) return kUART_16C1550;

    // Look for the FCR, which is present only in the 16750 and later
    OUTB(kREG_FIFOControl, kFIFO_Enable);
    OUTB(kREG_LineControl, 0x00);	/* Set DLAB=0 */
    OUTB(kREG_LineControl, 0xbf);	/* Set DLAB=1 */
    tmp = INB(kREG_LineControl);
    OUTB(kREG_LineControl, 0x00);	/* Set DLAB=0 */
    OUTB(kREG_FIFOControl, 0x00);
    if (tmp == 0x80) {
        DEBUG_IOLog("Apple16X50UARTSync::identifyUART() 0xBF Magic number accepted!\n");
        return kUART_16C750;
    }
    
    return kUART_16550C;
}

// XXX Need to move a few other functions here, like determineMasterClock()

#undef INB
#undef OUTB